Up to now, an eye fundus camera in which a light source for leading an eye to be examined to a predetermined image-taking region is provided and the eye to be examined is fixed to the light source to image-take the predetermined region of the eye to be examined has been known from, for example, Japanese Patent Application Laid-Open No. 8-252224.
FIG. 7 shows a structure of a conventional eye fundus camera. On an optical path after an objective lens 1 which is opposite to an eye to be examined E, a perforated mirror 2 having an aperture provided at the center thereof, a focusing lens 3, an image-taking lens 4, a swing mirror 5 which is swingable, a field lens 9, a field stop 10, an imaging lens 11, and an image pickup element 12 are disposed. In a reflecting direction of the swing mirror 5, a relay lens 6, a liquid crystal plate 7 in which lighting is possible at an arbitrary position to fix the eye to be examined E, and a light source 8 are disposed for a fixation optical system.
Also, on an optical path in an incident direction of the perforated mirror 2, a lens 13, a ring stop 14, and a light source 15 are disposed. Note that the ring stop 14 is disposed to be substantially conjugate to the perforated mirror 2 with respect to the lens 13. An output of the image pickup element 12 is connected with a control circuit 16. A television monitor 17, an image-taking switch 18, and a fixed index shifting switch 19 are connected with the control circuit 16. Here, a region 17a of the television monitor 17 is within a substantial field of the eye to be examined E.
In order to image-take a predetermined region of the eye to be examined E, an operator lights a predetermined position of the liquid crystal plate 7. At this time, positional information of the liquid crystal plate 7 is converted into an electrical signal, and a mark M1 is generated in a position obtained according to the information and synthesized on an observation screen of the television monitor 17 as shown in FIG. 8, so that it is viewed by the operator. In addition, in the case where the predetermined region is changed, the fixed index shifting switch 19 such as a cross key is used, for example, thereby shifting a lighting position of the liquid crystal plate 7. At this time, the mark M1 located on the observation screen is also shifted on the screen in conjunction with a shift of the lighting position of the liquid crystal plate 7.
However, according to the above conventional example, when an image pickup magnification of the eye to be examined E is changed, a size of an image to be examined is changed on a display device. Here, the fixed target position which is synthesized and outputted to the display device are not changed either before or after changing the magnification, so that the macular portion of the eye to be examined E and the fixed target position are deviated from each other. With this state, when the eye to be examined E is led again, there is a problem in that the operator is hard to lead it because the macular portion and the fixed target position are deviated from each other.
Also, when an image of the eye to be examined is magnified to center a papillary portion on the screen, there is also a problem in that the operator is hard to determine the direction in which a fixation lead to the eye to be examined E is conducted because the macular portion is located outside a display area on the display screen.